Effect of ethnicity on the progression of diabetic kidney disease independent of glycemic control

Background/aims: The prevalence of diabetic kidney disease (DKD) and risk of progression to end-stage renal disease is higher in African-Americans as compared to Caucasians. Whether the higher rate of estimated glomerular filtration rate (eGFR) decline in African-Americans is mediated by poor glycemic control is unclear.

Methods: We conducted a prospective study of 183 (African-American, n = 95; Caucasian, n = 88, mean age 66 +/- 10 vs. 70 +/- 11 years) patients with a diagnosis of DKD followed over a period of 12 months. eGFR (ml/min/1.73 m(2)) was calculated by MDRD formula and grouped into stage 1-2 (> or =60 ml/min), stage 3 (30-60 ml/min) and stage 4 (<30 ml/min). In addition, glycosylated hemoglobin A1C (HbA1c) was categorized into tertiles (<7, 7-8 and >8%) at each time point.

Results: There were no significant differences in eGFR at any time point between African-American and Caucasian in any stage of CKD during this period. There were also no significant differences in eGFR at any time point in each category of HbA1c.

Conclusions: Our data indicate that there were no ethnic differences in the rate of progression of DKD under equivalent glycemic control. Further research is needed to explore the mechanisms associated with higher prevalence and rapid progression of CKD in African-Americans compared to Caucasians.